Which attribute is primarily lowered as a consequence of quenching?

Quenching is a heat treatment process commonly used to harden metals. During this process, a metal is heated to a high temperature and then rapidly cooled, usually by immersion in water or oil. This rapid cooling causes the metal to undergo a transformation in its microstructure, leading to an increase in hardness.

While hardness increases, toughness, which refers to a material's ability to absorb energy and deform plastically without fracturing, is primarily lowered. The rapid cooling during quenching can introduce residual stresses and create a brittle structure in the metal, making it more susceptible to cracking under stress. As a result, the material becomes harder but much less tough.

Additionally, ductility—which refers to the ability of a material to deform under tensile stress—also decreases as a result of quenching. The transformation to a harder structure reduces the metal's ability to stretch or deform without breaking. However, the lower toughness aspect is more prominent in discussions of quenching effects compared to ductility. Thus, the primary attribute lowered in the quenching process is toughness, as the material becomes more prone to fracture and less capable of enduring impact or stress without failing.